May 2017

In a previous post, I explained that Cross-PDB DML, executing an update/delete/insert with the CONTAINERS() clause, seems to be implemented with implicit database links. Connecting through a database link requires a password and this blog post is about an error you may encounter: ORA-01017: invalid username/password; logon denied

I’m in sunny Phoenix this week at the Data Platforms 2017 Conference and looking forward to a break in the heat when I return to Colorado this evening.

As this event is for big data, I expected to present on how big data could benefit from virtualization, but was surprised to find that I didn’t have a lot of luck finding customers utilizing us for this reason, (yet). As I’ve discussed in previous presentations, I was aware of what a “swiss army knife” virtualization is, resolving numerous issues, across a myriad of environments, yet often unidentified.

Yesterday I made a short video to talk about my two day class " How to Perform a Security audit of an Oracle database " and added the video to YouTube. This class is going to be delivered at a....[Read More]

Headline – if you don’t want to read the note – the /*+ parallel(N) */ hint doesn’t mean a query will use parallel execution, even if there are enough parallel execution server processes to make it possible. The parallel(N) hint tells the optimizer to consider the cost of using parallel execution for each path that it examines, but ultimately the optimizer will still take the lowest cost path (bar the odd few special cases) and that path could turn out to be a serial path.

The likelihood of parallelism appearing for a given query changes across versions of Oracle so you can be fooled into thinking you’re seeing bugs as you test new versions but it’s (almost certainly) the same old rule being applied in different circumstances. Here’s an example – which I’ll start off on 11.2.0.4:

I have accepted an offer by the Accenture Enkitec Group to join them starting next month. That unit is a kind of ‘special force’ inside the large Accenture Corporation with particular expertise in Oracle Database and Oracle Engineered Systems technology.

Although I feel quite a bit sad to leave Oracle after all those years, the opportunity to work together with all these bright people – you can see some of them here – outshines that largely

I was not in the beta program for Oracle database 12c release 2 but when I was discussing security changes in the new release with some people who were in the beta they told me that O7_DICTIONARY_ACCESSIBILITY and utl_file_dir parameters....[Read More]

There are so many things that can go wrong when you start using tables with more than 255 columns – here’s one I discovered partly because I was thinking about a client requirement, partly because I had a vague memory of a change in behaviour in 12c and Stefan Koehler pointed me to a blog note by Sayan Malakshinov when I asked the Oak Table if anyone remembered seeing the relevant note. Enough of the roundabout route, I’m going to start with a bit of code to create a table, stick a row in it, then update that row:

Here are some SLOB LIO figures from a DB zone configured with 16 threads running on an Oracle SuperCluster M7 hardware. For comparison I've also included numbers from an Intel Xeon E5-2699 V4 CPU.

It makes sense to mention that this is not exactly a fair comparison -- a single SPARC M7 core has 8 threads associated with it so my zone is able to utilize a total of two SPARC M7 cores (16 threads total with 8 threads per core). E5-2699 V4 is currently top of the line Intel CPU core packed model with 22 cores. So we're comparing two SPARC M7 cores vs 16 E5-2699 cores. It does however help answer the question -- if you're running on a certain number of Intel cores what kind of performance can you expect when you move over to a heavy threaded M7 if you transfer your workload "as is"?

Happy National Goth Day! Although I consider myself “Goth Lite”, it’s a national holiday in my little world and I’m pondering what books I’ll write after I run out of tech titles. Needless to say, I’ve chosen the title, “Staying Geeky and Goth After 50” and chosen the following for the cover art: